1. Field of the Invention
This invention relates to a duo-binary and/or binary data slicer and more particularly but not solely to such a slicer capable of slicing the sound/data burst portion of the signal of a multi-standard MAC receiver. The invention is suitable for applications to DMAC, D2MAC and CMAC receivers.
2. Description of Related Art
In order to evaluate a binary or duo-binary signal it is necessary to establish a reference value with which the signal is compared to determine whether the instantaneous value of an incoming signal is representative of a binary 0 or 1. One way of doing this is to employ a capacitor which is charged to the peak value of a data signal and to compare the instantaneous incoming signal with that peak value.
In the case of composite signals such as are transmitted by MAC television transmitters only a small part of the period of a line signal contains binary or duo-binary data for evaluation and the amplitude of such data is often less than the amplitude of the colour difference signal component and luminance signal component. This difference in amplitude makes it difficult to define a suitable reference level. The present invention seeks to overcome this problem.